This invention relates generally to valves, and more particularly to a vent for use in a system for filling and emptying fluid storage tanks.
Fluid storage tanks, such as fuel tanks, may be provided with a vent valve which opens to vent the top of the tank to atmosphere when the tank is being filled or emptied, and a fill valve through which the fluid passes during such filling or emptying. The vent valve can be arranged so that it is opened by a mechanical actuator or by air pressure or by internal pressure in the tank. Examples of prior art fuel tank vent valves are shown in U.S. Pat. Nos. 3,144,056, 3,770,011, 3,771,549, and 3,981,325.